The present invention relates to cards using magnetic stripes, such as credit cards and debit cards, and more particularly, to devices and methods for swipe detection for use with swipeable computers having dynamic magnetic stripes.
Magnetic stripe cards have been in use since the 1960s. Since that time, the formats for storing and reading information on magnetic stripe cards have been standardized and the technology has been widely adopted. Some of the standards covering magnetic stripe cards include International Organization for Standardization (ISO) standards, ISO-4909, ISO-7810, ISO-7811, ISO-7812, ISO-7813, and ISO-8583. Based on these standards, millions of readers for magnetic stripe cards have been installed at merchants, points of service, and other locations worldwide.
To improve the functionality of magnetic stripe cards and still take advantage of the installed base of card readers, cards using dynamic magnetic stripes have emerged. These dynamic magnetic stripe cards function with the currently installed base of magnetic card readers and have several advantages including the ability to store and transmit information from multiple magnetic cards as well as the possibility for improved security.
Dynamic stripes must produce a time-varying magnetic field that duplicates the field produced by a non-dynamic stripe passing by the read-head. Creating this field requires energy and precise timing of the field variations. The process of detecting that a card user is swiping a dynamic card in a reader, along with the process of controlling the exact timing of the magnetic variations is collectively called “swipe sense.”
The quality of the swipe sense is determined by three metrics: 1) the frequency of “false alarms,” where the swipe sense falsely signals that a swipe is happening; 2) the accuracy of the timing (relative to read head position) of the signal from the swipe sense electronics; and 3) the average continuous power required by the swipe sense electronics.
Because dynamic magnetic cards are often designed at or near the dimensions of a standard credit card, they have limited space for a battery or other power source. The present invention relates to devices and methods for swipe detection that are used to reduce the power consumption associated with swipe detection in these devices without substantial degradation in the frequency of false alarms and timing accuracy.